| This paper consisted of three parts to discuss the effects of niacin and riboflavin on performance, body immunity and antioxidant capacity of dairy cows by way of duodenal perfusion.The first part measured dry matter intake and milk yield of dairy cows to study the effects of niacin and riboflavin on performance. The second part tested 18 indexes of peripheral blood and three kinds of immunoglobulins(IgA, IgG IgM) content in serum to estimate the influences of niacin and riboflavin on immunity of dairy cows.The third part discussed the effects of niacin and riboflavin on body antioxidant capacity of dairy cows by means of measuring the changes of oxidation stability indices,such as the activities of antioxidant enzymes and the contents of lipid peroxidation in serum.Experment one studied the effects of nicotinic acid and riboflavin duodenal infulsion on dry matter intake,milk yield and milk flavor in dairy cows. According to the principle of similar age, parity, milk yield, days in milk and weight,five primiparous Chinese Holstein cows(DMI=57 d±29 d,MY=18.9±1.3 kg/d,BW=562 kg±48 kg) fitted with duodenal cannulas were arranged in a 5×5 Latin square design and the administered 5 treatments were A:control check water(no nicotinic acid or riboflavin),infusion amount was 5 L/d;B:infusion amount was nicotinic acid 3 g/d; C:infusion amount was riboflavin 0.3 g/d; D: infusion amount was nicotinic acid 3 g/d and riboflavin 0.3 g/d; and E:infusion amount was nicotinic acid 3 g/d+riboflavin 0.3 g/d+thiamine 0.03 g/d+pantothenic acid 0.42 g/d+pyridoxine 0.03 g/d+biotin 0.04 g/d+folic Acid 0.04 g/d, respectively. The dairy cows were housed in individual tie stalls, and fresh water was provided for ad libitum consumption.Each period lasted 18 d, including 15 d adaptation and a 3 d of data collection.The results showed that the dry matter intake and milk yield were improved significantly,and body weight was unchanged by nicotinic acid and riboflavin blend and B-vitamin blend(p<0.05),but there were no effects of nicotinic acid or riboflavin(p>0.05). No difference was observed in milk flavor between treaments(p>0.05).It suggested that postruminal infusion of nicotinic acid and riboflavin at the same time can improve performance(p<0.05) and had no adverse effect on milk flavor,but there was no effect when they were used individually(p>0.05).Compared to control treatment A,milk from cows infused nicotinic acid and riboflavin blend or B-vitamin blend into duodenum had better flavor (p>0.05).So it speculated that nicotinic acid and riboflavin may have synergistic effect to improve the performance of dairy cows.Based on the experment one,experment two measured the influences of nicotinic acid,riboflavin on antioxidant capacity of dairy cows by assaying the levels of NA,NAM,riboflavin,MDA and TBARS,as well as T-AOC and the enzymes activities of CAT, T-SOD and GSH-Px in serum. The results indicated that nicotinic acid and VB blend can improve the levels of NA and NAM in serum significantly(p<0.05),although the datas may tend to increase by riboflavin and nicotinic acid+riboflavin,but there were no significant difference between treaments(p>0.05). All riboflavin and its blend could enhance the level of riboflavin in serum(p<0.05), but nicotinic acid had no effect on the level of riboflavin in serum, the data just tended to increase(p>0.05). Riboflavin, nicotinic acid+riboflavin and VB blend improved the activities of T-SOD and reduced TBARS content very significantly (p<0.01),significantly improved GSH-Px activities and T-AOC (p<0.05), but there were no significant influence on the CAT and MDA,just only CAT activities tended to decrease(p>0.05), and MDA reduced in riboflavin,nicotinic acid+riboflavin(p>0.05); Nicotinic acid extremely significant reduced TBARS content (p<0.01), but had no significant effects on T-SOD, GSH-Px, T-AOC, CAT and MDA (p>0.05),just had a role of promoting antioxidant enzymes activities and reducing MDA (p>0.05). When nicotinic acid, riboflavin were used together, they could enhance T-AOC,T-SOD and GSH-Px activities, reduce TBARS content much more useful than riboflavin used alone. This experiment suggested that nicotinic acid can reduce lipid peroxide reaction, promote antioxidant enzymes activity, decrease lipid peroxide; riboflavin can improve the antioxidant enzymes activity, enhance its scavenging free radicals ability, reduce lipid peroxidation and the accumulation of lipid peroxide, so that improved the antioxidation capacity of dairy cows. It had better effects when nicotinic acid, riboflavin were used together to improve the antioxidation capacity of dairy cows.Based on the experiment one,experment three collected peripheral blood and determined 18 indexes,separated serum and estimated the content of three immunoglobulins in serum to evaluate the effects of duodenal infusion of nicotinic acid and riboflavin on the immune function of lactating dairy cows. The results found that the content of red blood cells,hemoglobin and the percentage of neutrophilic granulocyte were extremely significant difference between treaments(p<0.01),but there were no significant effects of nicotinic acid and riboflavin on WBC parameters, platelet parameters and other RBC parameters (p>0.05).And just the total number of RBC and LYM, GRN and PLT tended to increase(p>0.05). Riboflavin and the blend with riboflavin could improve RBC(p<0.05),butnicotinic acid had no effect(p>0.05);When riboflavin and nicotinic acid were used together, the hemoglobin increased significantly (p<0.05), conversely had no significant changes when they were used alone. Riboflavin and nicotinic acid+riboflavin could improve the percentage of GRN(p<0.05),but nicotinic acid and the VB blend can not change the percentage of GRN(p>0.05). No difference was observed in serum IgA, IgM and IgG,but the content of three kinds of immunoglobulins tended to increase by nicotinic acid, riboflavin and their blend(p>0.05).This study demonstrated that post-ruminal infusion of nicotinic acid,riboflavin or their blend may be helpful for body to improve the immunity,and tend to increase blood cells related to immune function and the yield of Ig in blood. |
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